The prior art belt tightening device has the following elements. A body has a seat. Two ends of the seat are installed with a fixing hook and a movable hook. The fixing hook and movably hook are used to hook two sides of an object to be tied. A pull rod is pivotally installed to the seat. A wheel is rotatably installed to the pull rod. Two lateral sides of the wheel are installed with two stop claws. A belt winds around the wheel. In operation, the fixing hook and movably hook hook two sides of an object and then the pull rod is pulled so that wheel rotates with the pull rod to wind the belt so that the movably hook is tightened. When the pull rod is pushed back to the original position, since the pull rod has two stop claws, the wheel will not loose the belt. If the pull rod is pulled and release repeatedly, the belt will be tightened.
However if the tension is too great, the belt will break, but the prior art can be indicated the tension to the user so that the user cannot adjust the pull force to a proper value. Thereby there is an eager demand for a novel design which can improve the prior art defect.